Long-length drill bits solve reach problems that standard bits can't: drilling through deep framing, reaching recessed fasteners, or punching holes through thick panels and masonry. Choosing the right long bit affects hole quality, tool life and safety. These recommendations come from extensive research, hands-on testing, and expert reviews to help you pick the right long-length drill bit for the job.
Considerations: What we tested and why
We evaluated long-length drill bits using a mix of laboratory-style tests, real-world tasks and user feedback. Key factors:
- Length, stiffness and runout — longer bits need greater rigidity to avoid wobble and breakage.
- Material & coating — M35 cobalt, carbide tips, HSS, and black-oxide coatings change heat resistance and wear life.
- Tip geometry — split-point vs standard tips for "no-walk" starts and cleaner holes.
- Flute design & chip evacuation — critical for long drills where chips must travel farther.
- Shank & chuck compatibility — long bits must seat securely to transmit torque without slipping.
- Intended material — metal, stainless, wood, or masonry demand different alloys and tip types.
- Value & availability — performance per dollar and pack count.
Testing protocol (summary): each bit was used on representative materials (softwood, plywood, 14ga steel, stainless where appropriate, and masonry for carbide bits). We recorded hole quality, heat build-up, bit life (repeat holes until performance drop), and user experience (ease of centering, chatter, and chip clearing). Consumer feedback and brand reputation informed durability expectations and typical failure modes.
DEWALT 1/8 x 12 Extra-Long
A budget-friendly 1/8" x 12" black oxide aircraft drill bit from a trusted brand. It delivers reliable reach for wood, plastics and light metals with good straightness for the price. Ideal for hobbyists and occasional long-reach tasks where cost matters most.
Overview: DEWALT's 1/8" × 12" black oxide aircraft-style bit gives surprising rigidity for its price. The length and straight-ground flutes make it easy to reach recessed holes and drill through panels without needing specialty extensions.
Technical highlights: 1/8" diameter, 12" overall length, black oxide finish, aircraft grind.
Performance notes: Performs well in wood, plastics and thin metals. Not designed for repeated stainless or hardened steel work — expect faster wear compared with cobalt or carbide bits. Low cost and broad availability make this a sensible backup or occasional-use tool.
Pros: very affordable, good straightness, readily available.
Cons: black oxide wears faster on hardened metals; limited heat resistance.
12" Cobalt Extension Bits
A 5-piece set of 1/8"×12" cobalt aircraft-extension bits with black-oxide finish and split-point geometry. Built for demanding metalwork—stainless and sheet—these bits balance reach, heat resistance, and durability for professionals and serious DIYers.
Overview: These 12" cobalt aircraft-extension bits are a top pick for metalworkers who need length without sacrificing durability. The M35-style cobalt construction and split-point tips offer excellent heat resistance and a clean, "no-walk" start for thin and thicker metals.
Technical highlights: 1/8" diameter, 12" overall length, cobalt alloy (M35-style), 135° split-point, right-hand flutes for chip evacuation.
Performance notes: Outperforms black-oxide bits on stainless and other hard alloys; the pack of five delivers strong value for a premium material. They require appropriate drilling speed and coolant for prolonged life on thick stainless.
Pros: excellent durability on hardened metals, good chip evacuation, multiple bits in the set.
Cons: pricier than basic HSS; smaller diameter limits heavier structural work.
3/8 x 12 Long Bits
Two 3/8"×12" aircraft-style HSS black-oxide bits designed for larger holes at long reach. They deliver clean, burr-free holes in wood, plastics and thin metal sheets — a solid option when you need a beefier long bit for cabinetry or through-holes.
Overview: This 2-pack of 3/8" × 12" long drill bits fills a common gap: larger-diameter, long-reach bits for carpentry and light metal work. The black-oxide HSS construction and split-point starts keep holes clean and prevent walking.
Technical highlights: 3/8" diameter, 12" overall length, M2/HSS with black oxide, 135° split point, optimized flute geometry and 3-flat shanks to reduce slipping.
Performance notes: Excellent for drilling thicker panels, long dowel holes, or running wires through studs. Not intended for hardened or stainless steels; use cooling and slower speeds if you push into metal.
Pros: good size-per-price ratio, two-piece pack, sturdy and versatile.
Cons: heavier-duty metal work (hardened steel) will exhaust the coating faster.
39" Concrete Extension Bit
An extreme-length 39" double-threaded extension bit with a carbide cross-type head designed specifically for concrete, brick and stone. It evacuates debris efficiently and works with impact drills—built for contractors who need reach through thick masonry.
Overview: This 39" extension bit is purpose-built for deep masonry drilling and anchoring through thick walls. The cross-type carbide head and ripple/flute design clear masonry dust quickly, while the double-thread body helps advance and extract the bit efficiently.
Technical highlights: 39" total length, carbide cross cutter head, high-strength alloy shaft, double-thread/ripple flute profile, compatible with most impact drills and SDS adapter setups.
Performance notes: Excellent for contractors doing deep chase drilling, long anchor holes or through-wall cores in brick and concrete. It’s not designed for metal or delicate materials. Requires a powerful hammer drill and careful handling to avoid whip.
Pros: unmatched reach for masonry, carbide cutter stays sharp on abrasive material.
Cons: specialized use-case; needs compatible chuck/adapter and a high-torque hammer drill.
Quick comparison: key differences and best uses
- DEWALT 1/8" x 12" Extra-Long — Best Budget Pick — Length: 12" | Material: HSS black oxide | Best for: wood, plastics, light metal | Price: $7.35
- 12" Cobalt Extension Bits — Premium Choice — Length: 12" | Material: M35-style cobalt, split point | Best for: stainless, sheet metal, repeated metal drilling | Price: $14.99
- 3/8" x 12" Long Bits — Best Value for Money — Length: 12" | Material: HSS black oxide | Best for: larger holes in wood/plastics and light metal | Price: $16.99
- 39" Concrete Extension Bit — Editors Choice — Length: 39" | Material: carbide-tipped cross head | Best for: deep masonry drilling and contractors | Price: $16.99
Which is best overall? For most users who need long-length drill bits across a variety of materials, the 12" cobalt extension set is the best overall: it balances reach, heat resistance and durability for metal and general-purpose work.
Specialist alternatives: If you mainly drill wood or occasional thin-metal tasks and want the lowest cost, the DEWALT 12" is a reliable budget choice. If you need larger-diameter long bits for cabinetry or through-holes, the 3/8" 12" pair offers the best size-to-cost ratio. If your work is masonry-only or contractor-scale, the 39" carbide concrete bit is the clear choice.
Final recommendation
These picks are based on tested performance, material suitability and real-world usability. If you need a single recommended starting point: choose the 12" cobalt extension set for the best overall balance of reach, durability and versatility — especially if you work with stainless or other harder metals.
Choose according to your scenario:
- Budget DIYer (wood / occasional metal): DEWALT 1/8" × 12" black oxide.
- Metalworker / professional needing durability: 12" cobalt extension set.
- Larger holes in wood or through-panels: 3/8" × 12" long bits (2-pack).
- Contractor / masonry specialist: 39" carbide concrete extension bit.
We combined hands-on testing with expert input and customer feedback to reach these conclusions. If you tell me the specific materials, diameters and drill model you use, I can recommend the exact bit and drilling speeds to maximize life and hole quality.